Source

www/scale.html

<h3>Whatever size you need it to be</h3>

- <p>"Scalability" is an often-misused word on the Web. Scaling is not the same as being fast, and it is not the same as being large. To say meaningfully that something scales, you must do so in terms of some numerically measurable feature (throughput, latency, volume, anything you can describe with a single number) and some other numerically measurable resource that presumably costs you money (such as the number of computers being used). To say that something scales is to say that there is a relationship between that resource and that feature which remains constant regardless of how much you increase the numbers. This is practically useful because it gives you predictable cost ceilings when your needs grow. If there is no such useful resource/benefit relation, your system does not scale. (and if turning the dial way up on your scaling factor causes some other aspect of your system to perform much worse, your system's scalability is questionable at best)</p>

+ <p>"Scalability" is an often-misused word on the Web. Scaling is not the same as being fast, and it is not the same as being large. To say meaningfully that something scales, you must do so in terms of some numerically measurable feature (throughput, latency, volume, anything you can describe with a single number) and some other numerically measurable resource that presumably costs you money (such as the number of computers being used). To say that something scales is to say that there is a relationship between that resource and that feature which remains constant regardless of how much you increase the numbers. This is practically useful because it gives you predictable cost ceilings when your needs grow. If there is no such useful resource/benefit relation, your system does not scale. (If turning the dial way up on your scaling factor causes some other aspect of your system to perform much worse, your system's scalability is questionable at best.)</p>

<p>One important way in which Riak scales is in the relationship between total storage capacity and the number of disk-containing servers in the cluster. If your cluster has a given total capacity of some number "C", and is comprised of "N" servers (which roughly equivalent amounts of disk in each) then you can double your capacity by doubling your number of servers -- no matter what the original values of C and N.</p>